selftests/bpf: test_progs/sockopt_sk: Remove version

As pointed by Andrii Nakryiko, _version is useless now, remove it.
Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210408061310.95877-1-yauheni.kaliuta@redhat.com

tools/testing/selftests/bpf/progs/sockopt_sk.c

@@ -6,7 +6,6 @@
 #include <bpf/bpf_helpers.h>
 
 char _license[] SEC("license") = "GPL";
-__u32 _version SEC("version") = 1;
 
 #ifndef PAGE_SIZE
 #define PAGE_SIZE 4096